The blast that killed a Palestinian ambassador to the Czech Republic at his Prague residence was an accident, police said.
Prague police said the explosion on Wednesday morning was likely caused by an anti-theft system on the door of a safe that Jamal al-Jamal was opening at the time.
The 56-year-old suffered serious injuries in the blast and was taken to Prague's military hospital in an artificial coma, said Jirina Ernestova, spokeswoman for the emergency services.
Minutes after opening the safe the explosion took place, causing serious injury to Jamal who was taken to hospital and operated on.
His family was also at the two-storey residence, in a northern suburb of Prague, but no one else was hurt, although officials said his wife was taken to another hospital to be treated for smoke inhalation and stress.
"According to information from the investigation so far, this was definitely not a terrorist attack," national police president Martin Cervicek said on Czech Television.
The Palestinian foreign ministry, said in a written statement that the blast happened minutes after Jamal opened a safe that had come from the embassy's old offices.
Police spokeswoman Andrea Zoulova the blast was triggered when the door of the safe was opened.
"The possibilities include inexpert handling of an explosive device or its spontaneous detonation," Zoulova said. "The device was in a safe."
Police cordoned off part of the street as emergency services attended.
Daniel Langer, surgeon at the Prague military hospital to which Jamal was taken, told Czech television the ambassador had suffered devastating head, stomach and chest injuries.
Jamal, who took office in October, had only recently moved to the new residence on the northern outskirts of Prague.
Riyad al-Malki, the Palestinian foreign minister, hailed him as an exemplary diplomat, who served his country and cause well.
The Palestinian foreign ministry said the blast occurred on as Jamal was opening an old safe which had been brought from the previous embassy building to the new one.
"Minutes after opening the safe the explosion took place, causing serious injury to Jamal who was taken to hospital and operated on," the ministry said in a written statement.
Zoulova said police were not ruling out the possibility the safe was mishandled.
Police searched a building next door which also belongs to the Palestinian embassy, but said they had not found any other explosives in the area.
Cervicek told the private Nova television station that police would investigate the case further. A Palestinian team had arrived in Prague to take part in the investigation.
Jamal was born in Beirut in 1957 to a Palestinian family that had fled Jaffa, near modern-day Tel Aviv, after the state of Israel was created in 1948, and moved to Shatila refugee camp in Lebanon.
He joined the Fatah party in 1975 and became an aide to the ambassador in Bulgaria four years later. He moved to Prague as a diplomat in 1984.
After working as Palestinian consul to the Egyptian port city of Alexandria from 2005, he was appointed ambassador to the Czech Republic in October 2013.